Information Processing System and Method of Allocating I/O to Paths in Same

2. The information processing system according to claim 1 , wherein the first processing unit recalculates the weights W i when load change in the path P i has exceeded a threshold value, the second processing unit obtains again the I/O issue interval d i , based on the weights W i thus recalculated, the third processing unit obtains again the I/O issue timings t i (m), based on the once again obtained I/O issue interval d i , and the fourth processing unit issues the I/Os to the paths P i in an order corresponding to an order of the once again obtained I/O issue timings t i (m) chronologically arranged.

3. The information processing system according to claim 1 , wherein the first processing unit sets the weights W i according to loads on and performance of the respective paths P i .

4. The information processing system according to claim 1 , wherein the paths P i are identified by a combination of a network port of the information processing system, a network port of the storage apparatus, and a network port of a switch interposed between the network ports of the information processing system and the storage apparatus.

5. The information processing system according to claim 1 , wherein the fourth processing unit issues the I/Os in an order giving priority to the path P i having a lower load among the paths P i having coinciding I/O issue timings t i (m), when there are paths P i that have coinciding I/O issue timings t i (m), the coinciding I/O issue timings t i (m) being the I/o issue timings t i (m) of different ones of the paths P i that coincide with each other as a result of arranging the I/O issue timings t i (m) in chronological order.

6. The information processing system according to claim 1 , wherein the fourth processing unit issues the I/Os in an order giving priority to the path P i having a higher performance among the paths P i having coinciding I/O issue timings t i (m), when there are paths P i that have coinciding I/O issue timings t i (m), the coinciding I/O issue timings t i (m) being the I/O issue timings t i (m) of different ones of the paths P i that coincide with each other as a result of arranging the I/O issue timings t i (m) in chronological order.

7. The information processing system according to claim 1 , wherein the fourth processing unit cyclically replaces the path P i given priority to issue the I/Os among the paths P i each time an I/O issue timing t i (m) coincides, when having cyclically coinciding I/O issue timings t i (m), the cyclically coinciding I/O issue timings t i (m) being the I/O issue timings t i (m) of different ones of the paths P i that coincide with each other as a result of arranging the I/O issue timings t i (m) in chronological order.

9. The method of allocating an I/O to paths in an information processing system according to claim 8 , wherein the information processing system recalculates the weights W i , by performing the first step again, when load change in the path P i has exceeded a threshold value; obtains again the I/O issue interval d i based on the recalculated weights W i by performing the second step; obtains again the I/O issue timings t i (m) based on the once again obtained I/O issue interval d i by performing the third step; and issues the I/Os to the paths P i in an order corresponding to an order of the once again obtained I/O issue timings t i (m) chronologically arranged, by performing the fourth step.